As a urine analyzer used in urine tests, a urine qualitative analyzer and a urinary particle analyzer are widely known. A urine qualitative analyzer is generally constructed in such a manner that a test paper having a reaction test piece stuck thereon for each measurement item is immersed in an analyte urine sample for a predetermined period of time, and the color of the test piece is compared with standard colors for determination so as to obtain the results of negative/positive (−), (±), (+), . . . automatically for each item (See, for example, Japanese Laid-open Patent Publication No. 2-27262). Also, a urinary particle analyzer is constructed to classify and count the particles in an analyte urine sample automatically (See, for example, U.S. Pat. No. 5,325,168).
One of the measurement items of the urine qualitative analyzer such as described above is protein concentration. Since protein is reabsorbed by renal tubes in the normal kidney, this protein concentration is used as an index that indicates the reabsorption capability of the kidney. However, depending on the condition of a patient (person to be tested), the urine is sometimes concentrated or diluted, so that it may not be possible to grasp the amount of excreted protein in urine correctly by random urine. By a current protein test paper, with a diluted urine, a clinically significant proteinuria (namely, a specimen that should be evaluated as being positive) may be evaluated as being negative or conversely, with concentrated urine, those that should be evaluated as being negative may be evaluated as being positive.
In view of the above, a method is proposed in which a creatinine concentration in an analyte urine sample is measured by the colorimetry so as to correct the result of measurement of the concentration of albumin, which is one kind of protein, with the creatinine concentration (See U.S. Pat. No. 6,306,660). Since this creatinine concentration reflects the degree of concentration of the urine, such correction can remove the influence of concentration or dilution of the urine from the result of measurement of albumin concentration.
However, with the above-described method of correction of the protein concentration disclosed in U.S. Pat. No. 6,306,660, the creatinine concentration is measured by the colorimetry; however, the creatinine concentration measurement using the colorimetry such as described above has a low resolution due to its structure, thereby raising a problem of low correction precision.